Self-expansion bag type expansion anchor rod supporting structure and construction method

The self-expansion bag type expansion anchor rod supporting structure comprises an anchor rod body, the bottom of the anchor rod body is sleeved with a fixing cylinder, the outer wall of the fixing cylinder is sleeved with a bag, the top of the fixing cylinder is provided with a grouting device, and the top of the fixing cylinder is in threaded connection with the anchor rod body through an upper fixing device; a limiting device is arranged at the top of the anchor rod, a protection head is connected to the bottom of the anchor rod through threads, an extending cylinder is in sliding contact with the interior of the limiting hole, a plurality of grouting holes are formed in the middle of the outer wall of the extending cylinder in the circumferential direction at equal intervals, and a clamping ring is fixedly connected to one end of the extending cylinder; the other end of the extension cylinder is fixedly connected with a limiting ring which is matched with the annular groove. The extension cylinder can be